ANSI standard C12.22, which specifies a method for transmitting metering information, discloses a method in which a device for transmitting a communication message transmits the communication message after establishing routing information for determining which transfer device should relay the information.
Further, this standard specifies that an encryption key for encrypting a communication message should be previously shared among terminals, but does not specify a framework to dynamically set or update (re-key) the encryption key.
Accordingly, there is a problem that a malicious third party guesses the encryption key to analyze the encrypted communication message when the same encryption key is used for a long time to continue communication. Further, it is difficult for a meter device, which is generally formed as an embedded device having a low processing capacity, to simultaneously carry out a plurality of processes such as establishing the routing information and exchanging the encryption key, for example, while incorporating the encryption key into a device registration message for establishing the routing information.
Accordingly, the encryption key may be set by using the framework of an encryption key exchange protocol such as IKE (Internet Key Exchange protocol) and TLS (Transport Layer Security) after the communication route is established, which however leads to a problem that communication traffic and processing volume between the devices are excessively increased.